Experimental Study On Bonding Performance Of High Strength Mechanical Sand Concrete With Steel Tube

The concrete-filled steel tube has the advantages of high carrying capacity,high deformation and energy dissipation capacity.The economic effect of the high-rise building constructed by this structure has become a widely used architectural form in engineering application.With the increasing demand for construction sand,China's natural river sand resources are increasingly scarce,there have been short supply situation,therefore,to seek alternative sand sand is particularly important.The use of rock resources or engineering waste rock production mechanism of sand,can be part or all to replace the natural river sand preparation of high strength concrete,and the combination of steel pipe to form a high strength steel pipe concrete structure.In this paper,54 steel pipe high-strength concrete concrete specimens were prepared by using the method of launching test to study the bonding mechanism,the bond stress and the longitudinal slip along the longitudinal direction of the concrete,and consider the raw material form(limestone,Pebble),concrete strength,stone powder content,diameter ratio and other factors on the mechanical properties of steel pipe sand interface.On this basis,the binder-slip constitutive model of concrete with high strength steel pipe is put forward.The main research contents are as follows:(1)The load-slip curve of each specimen can be obtained by the test of the concrete specimen with high strength steel pipe,and the typical load-slip curve can be obtained by analyzing the load-slip curve.It is found that the shape of the raw material has a great influence on the shape of the load-slip curve.The PS curve of the machine is the limestone specimen,and its PS curve is gentle after the peak point,and there is no obvious descending section.The raw material is pebble The PS curve of the specimen has a significant descent after the peak point.(2)Through the continuous arrangement of the displacement gauge and the resistance strain gauge in different positions in the longitudinal direction of the steel pipe,the variation law of the steel pipe strain and slip along the height direction of the steel pipe during the whole launch test is measured and the steel pipe concrete The strain-slip curve,analysis and induction curve characteristics of the specimen can be obtained by the test of the concrete specimen with high strength steel pipe,and the size and distribution of the bond stress are obtained.Its typical load-slip curve.It is found that the shape of the raw material has a great influence on the shape of the load-slip curve.The PS curve of the machine is the limestone specimen,and its PS curve is gentle after the peak point,and there is no obvious descending section.The raw material is pebble The PS curve of the specimen has a significant descent after the peak point.(3)The influence of the factors such as the shape of raw materials,the content of stone powder,the strength of concrete,the ratio of thickness to thickness on the adhesion of steel pipe sand concrete and the law of bond strength were studied.(4)Through the analysis of the average bond stress-free end slip curve of the specimen,the average bond stress-free end slip constitutive model is proposed.After comparing with the experimental results,it is found that the two are in good agreement Verify its rationality.On the basis of this,the bond-slip constitutive relation considering the position change is proposed based on the average bond stress-free-end slip curve as the reference curve.